I've had ongoing problems syncing my Centro with my HotSync cable, and hadn't had a successful sync since May (although I'd only tried a few times). In the past, I've often used the trick of bringing up PocketTunes to confirm that I could mount the SD card on my PC. Then having done that, I'd switch to the HotSync application, and being very careful not to move the Hotsync cable, I would successfully hotsync.

Yesterday I tried this tactic a number of times, and did indeed successfully mount my SD card via PocketTunes, but was still unable to Hotsync despite killing and restarting the HotSync process in Windows. Of course I was fiddling with the hotsync cable at various angles to try to get this to work.

Then when I was driving around later, I discovered that my Centro was caught in a Hotsync loop, as others have described, e.g. here:
Treo 650 hotsyncs in a loop - Palm - Wireless Forums from AT&T

I soft-reset it, but this didn't help, and I really didn't want to perform a hard reset since it's been three months since I've had a successful sync/backup!

After fiddling with the Hotsync settings and holding/pushing a bunch of keys near the bottom of the keyboard (as I found recommended somewhere), the Hotsync loop stopped. Of course if I'd been smart, I would've run an NVBackup at that point. But instead, I continued to fiddle, and now my Centro won't boot at all, despite multiple battery removals and attempts at charging. The red light goes on when plugged into the charger or hotsync cable, but that's it.

At this point I'd be happy to boot it once, perform an NVBackup, and hope to recover as much (of my calendar&contacts) as I can onto an old Sprint 650 (I have four more months until I'm eligible for a Pre upgrade).

This is rather an urgent situation for me time-wise.

Thanks in advance for your advice ...